Method and apparatus for cleaning selectively fused master

ABSTRACT

A roller having a relatively long napped loose-woven limp fabric on the surface thereof is rotated against the surface of a selectively fused electrostatic master to remove unwanted partially fused specks of material. The roller is rotated partially submerged in a liquid into which the removed material is deposited.

United States Patent Inventor Frederick E. Barr Chesterland, Ohio Appl.No. 883,012

Filed Dec. 8, 1969 Patented Dec. 28, 1971 AssigneeAddressograph-Multigraph Corporation Cleveland, Ohio METHOD ANDAPPARATUS FOR CLEANING SELECTIVELY FUSE!) MASTER 8 Claims, 2 DrawingFigs.

US. Cl 134/9, 15/77, 96/1, 355/15 Int. B08b 1/02, 003g 15/00 Field ofSearch 134/6, 9; 117;37 LE/; l5/77, 100, 102; 355/15; 101/416, 423, 425

[56] References Cited UNITED STATES PATENTS 1,454,703 5/1923 Cohen15/100 3,128,683 4/1964 Rubin 96/1 X Primary Examiner-Morris O. WolkAssistant ExaminerD. G. Millman Attameys- Russell L. Root and Ray S.Pyle ABSTRACT: A roller having a relatively long napped loosewoven limpfabric on the surface thereof is rotated against the surface of aselectively fused electrostatic master to remove unwanted partiallyfused specks of material. The roller is rotated partially submerged in aliquid into which the removed material is deposited.

IIIIIIIIIIIIIIIIIIIIII BACKGROUND OF THE INVENTION This inventionrelates generally to the cleaning of masters and more particularly tothe removal of unwanted partially fused specks from selectively fusedelectrostatically produced masters.

In the production of electrostatically developed masters, a master formis provided which has a chemical coating that normally maintains acharge on the surface thereof, but which coating will lose its surfacecharge when exposed to light. After the master is uniformly charged overits surface, the object to be copied is projected in a pattern of lightand dark, or is placed between a light source and the master so thatprinted or opaque material on the original will block the light fromstriking the surface, whereas the background will permit the light tostrike the surface of the coating. The areas blocked from the light willretain their charge while the areas exposed to the light will lose theircharge.

Particles capable of being attracted to the charge on the surface arethen brought into contact with the surface of the coating. Where thecharge remains, these particles will adhere to the surface and where nocharge remains, the particles will not adhere. This then provides adistribution of the particles on the surface of the coating whichcorresponds to printed or opaque material on the original. At thisstage, however, the particles adhering to the surface are merely heldthereon by electrostatic attraction, and hence they must be set orpermanently fixed by fusing. The step of fusing is done by applying heatto the particles causing them to fuse together and to adhere to thecoating.

One of the problems encountered with the process of electrostaticallyforming an image is the appearance of unwanted spots on the surface ofthe coating. There spots can be caused by many different phenomena. Thecoating itself may have small defective areas which do not properly losetheir charge when exposed to light; the original may have small spots orimperfections thereon which are not intended to be reproduced; or dustor dirt or other particles may block the light at unwanted places.These, plus other factors, can contribute to unwanted specks.

When the master is set by the process known as selective fusing, theseunwanted spots can be removed. In the process of selective fusing, thesurface of the master is moved relative to an infrared light source. Theheat from the infrared light strikes the particles causing them to heatup. When the particles heat up, the particles also radiate heat betweenthemselves, and so the combination of the heat from the light source andthe radiation between the particles themselves cause the particles tofuse. In such a case, a large mass or group of particles will radiatemore heat between themselves than a smaller mass, and thus in any giventime a larger area of particles will become more completely fused thansmaller areas of particles. Hence, by controlling the time of exposureto the infrared light, groups of particles smaller than any given sizecan be incompletely fused, whereas groups of particles larger than thisgiven size will be completely fused. Hence, by controlling the time ofthe exposure a group of particles smaller than for example a normalpunctuation period can be incompletely fused and thus susceptible toremoval, whereas groups of particles larger than this size can becompletely fused and thus inpervious to removal.

In the past, these incompletely fused areas have not been removed as thesurface is prepared for use as a lithography master by bringing them incontact with a hard rubber roller or with a short nap tightly woven feltroller. This prior art technique is effective for partial removal tosome degree, but has the serious limitation that the rollers themselvessoon become filled or clogged with the removed particles. Since theparticles are abrasive, when they are retained by the roller they willscratch the coating on the surface of the master with detrimentaleffects. Even rotating the rolls in a solution has not been asatisfactory answer to this problem, since the rollers still tend toremain filled and clogged.

SUMMARY OF THE INVENTION According to the present invention, a methodand apparatus for removing the partially fused particles from the masteris provided which utilizes a relatively long napped loose, limp materialwhich is at least partially submerged in a liquid and which isrelatively movable across the surface of the master to remove thepartially fused particles therefrom. In the preferred embodiment, thematerial is mounted on a roller partially submerged in a liquid androtated in contact with the surface of the master is moved therepast.The use of a long napped, loose limp material allows the particlesremoved thereby to be dispersed into the liquid and thus preventsclogging.

DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of an apparatusaccording to this invention adapted to remove partially fused particlesfrom an electrostatically developed master; and

FIG. 2 is a sectional view taken substantially on the plane designatedby line 2-2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, apreferred embodiment of an apparatus for cleaning selectively fusedmasters is shown. The apparatus includes a housing designated generallyas I0 having a master receiving opening l2 and a master dischargeopening 14. Contained within the housing 10 are a pair of receivingrolls 16 and 18 located adjacent to receiving opening 12 and a pair ofdischarge rolls 20 and 22 located adjacent the discharge opening 14.These rolls 16, I8, 20 and 22 are each mounted by suitable means torotate in the directions as indicated in FIG. 2 and are driven by amotor not shown. Interposed between the receiving rolls I6, 18 and thedischarge rolls 20, 22 is a roller member 24. The roller member 24 isalso rotatably mounted and driven by the motor in the direction shown bythe arrow. The roller member 24 is provided with a surface covering ormaterial 26 which is long napped fiber. The fibers of the material areloose and limp (i.e., they are lacking in stiffness, flacid andflexible) so that they will not scratch the surface of the master, norwill they form a tight structure which will capture and retain loosenedparticles.

The roller member 24 is positioned so that the lower portion thereofextends into a trough 28 which is partially filled with a liquid 30maintained at a constant level by a replenishing bottle 32. To guide themaster through the trough 28, a guide 34 is provided which is shaped toengage the master as it emerges from the receiving rolls and guide itthrough the trough 28 in contact with the fabric 26 on the roll 24, andthence out of the trough and into the discharge rolls 20 and 22.

In the operation of this device, the trough is filled with any suitableliquid. This liquid could be merely water; however, since the coating ofthe master normally needs to be treated so that the background canbecome hydrophilic and oleophobic the liquid preferably is of the typewhich is used in the process for so treating the coating.

In operating the device, the master is fed face up through the receivingrolls 16 and 18. The guide 34 will guide the master through the trough28 with the roller member 24 rotating the fabric 26 in contact with thesurface of the master. The path of travel is shown in dotted lines.

It is preferred that the roller member 24 be rotated so that it istraveling in the same direction as the lineal direction of travel of themaster where it contacts the master. The linear speed of rotation of theroller member 24 should be substantially greater than the speed of themaster where they are in contact. This will allow the long napped looseand limp material 26 to flail against the surface of the master and dragthereacross. This flailing and dragging action will be effective toremove the partially fused small particles but will not remove thecompletely fused larger areas of particles. This type of materialutilized in this manner also prevents the fabric 26 from becomingclogged with particles which it removed, the particles actually beingdeposited in the liquid 30.

As explained above, with prior art devices such as close weave short napfabrics, such as felt, the fabric itself picks up and retains theparticles even in the presence of a liquid and hence in a short periodof time scratches the surface. With the present-type device, there is noclogging of the fabric so that the fabric can continue to operate as aremoval vehicle without collecting the particles which it removes. Thereasons for the superiority of the present device, in that it does notbecome filled or clogged with particles, are not completely understood.However, it is believed that such superiority is due at least in part tothe fact that the long, loose, limp nap is not inherently tight and firmenough to retain the particles, and hence the material acts rather likea flail dragging across the surface of the master and wiping thepartially fused particles from the surface. As the particles areloosened, they are not captured by the weave of the fabric, since thenap is loose and long, so the particles are deposited directly in thesolution. With the prior art felt-type rollers, the roller was stronglyurged into contact with the surface of the master. This type ofoperation results in the particles being forced into the nap of thefabric as they are being removed, and the tight weave short napstructure of the felt tends to hold or retain the particles so forcedtherein. This results in clogging the roll. Hence, by virtue of the factthat the present invention employs a long and loose, limp fiber, theconditions which contribute to clogging are not present.

What is claimed is:

1. A method of removing partially fused small particles from anelectrostatically developed image on a surface, comprising the steps ofproviding a material having a long nap, loose limp fiber structure, atleast partially submerging said material in a liquid, and causing saidsurface and said submerged portion of said material to move relativelyin contact, whereby the material will remove any small partially fusedparticles from the surface and said particles will be deposited in theliquid.

2. The method of claim 1 wherein said material is disposed on thesurface of a roller, and said roller is rotated so that it moves incontact with said surface.

3. The method of claim 2 wherein said surface is moved relatively withrespect to the rotating roller.

4. The method of claim 3 wherein said roller is rotated in the samedirection as the surface where said material contacts said surface.

5. A device for removing partially fused small particles from anelectrostatically developed image on the surface of an articlecomprising, a member having a long nap loose limp fiber material, troughmeans adapted to contain liquid means mounting said member with thematerial at least partially disposed therein, and means disposed to movethe article and said member relatively with said surface of said articlein contact with the material disposed in the trough.

6. The invention as defined in claim 5 wherein said member is a rollerhaving said material on the surface thereof.

7. The invention as defined in claim 5 wherein said means to move saidarticle and member includes means to move said article past said member.

8. The invention as defined in claim 5 wherein said member is a rollerwith the material on the surface thereof, and means to move the articleand said member includes means to rotate said roller.

2. The method of claim 1 wherein said material is disposed on thesurface of a roller, and said roller is rotated so that it moves incontact with said surface.
 3. The method of claim 2 wherein said surfaceis moved relatively with respect to the rotating roller.
 4. The methodof claim 3 wherein said roller is rotated in the same direction as thesurface where said material contacts said surface.
 5. A device forremoving partially fused small particles from an electrostaticallydeveloped image on the surface of an article comprising, a member havinga long nap loose limp fiber material, trough means adapted to containliquid means mounting said member with The material at least partiallydisposed therein, and means disposed to move the article and said memberrelatively with said surface of said article in contact with thematerial disposed in the trough.
 6. The invention as defined in claim 5wherein said member is a roller having said material on the surfacethereof.
 7. The invention as defined in claim 5 wherein said means tomove said article and member includes means to move said article pastsaid member.
 8. The invention as defined in claim 5 wherein said memberis a roller with the material on the surface thereof, and means to movethe article and said member includes means to rotate said roller.